Noscapine, CAS # 128-62-1, is used in cough suppressants in Japan and throughout the Asian continent. Noscapine is a natural product found in opium that can cross the blood-brain barrier to exert its effect upon the central nervous system, resulting in cough suppression. In addition, noscapine has been shown in animal studies to reduce tumor growth, and exploratory research into the use of noscapine as an anti-tumor agent is ongoing.
Noscapine, as shown in FIG. 1, may be extracted from crude opium. In addition, other substances such as morphine may be present in the crude opium. Morphine is a controlled substance subject to governmental control in many localities, and the amount of crude opium available to a particular producer of noscapine may be limited by the amount of morphine in the crude opium. Therefore, the manufacturing capacity of the noscapine producer using crude opium as a noscapine source may be limited by governmental rules related to the morphine content of the crude opium.
To address this limitation, noscapine manufacturers have turned to alternative sources of noscapine, such as poppy straw, which is a mixture of stems and capsules from the harvested opium poppy, Papaver somniferum. Depending on the particular strain of poppy and the post-harvest processing of the poppy straw, the poppy straw may have a much higher proportion of noscapine content relative to morphine content.
However, poppy straw may additionally contain a number of impurities such as papaverrubine compounds. Papaverrubine compounds may irreversibly transform into red iminium salts under acidic conditions, as shown in FIG. 2. When present in purified noscapine products, the red iminium salts impart an undesirable reddish color to the noscapine product. Unfortunately, most current methods of noscapine extraction and purification involve dissolving the crude noscapine source into an acidic solution.
A need exists to develop a method of separating noscapine from an opium source that may contain papaverrubines or other impurities that undergo irreversible color changes when exposed to acidic process conditions.